A decision on the murder conviction of Robert (Willie) Pickton will be announced Thursday. The Port Coquitlam pig farmer was convicted of six counts of second degree murder. (CBC)

The B.C. Court of Appeal will render its decision on the appeal by convicted serial killer Robert William Pickton on Thursday at 10:30 a.m. PT.

Pickton, a Port Coquitlam pig farmer, was found guilty of six counts of second-degree murder in December 2007 in the deaths of Sereena Abotsway, Mona Wilson, Andrea Joesbury, Georgina Papin, Marnie Frey and Brenda Wolfe.

He was sentenced two days later to life in prison with no chance of parole for 25 years. Both the Crown and the defence appealed the decision.

Pickton was initially supposed to be tried for 26 counts of first-degree murder, but Justice James Williams split off six counts from the other 20, which were to be tried at a later date.

In January 2008, Pickton’s lawyers launched an appeal, arguing a new trial for six counts of second-degree murder should be granted.

If Pickton wins his appeal, according to UBC law professor Janine Benedet, all six convictions would likely be quashed until a new trial could begin.

"That doesn’t mean he is acquitted, [that] he is set free," Benedet said. "He is still charged with all those [26 murder] charges. He'd have to apply for bail … which is highly unlikely he would receive."

The Crown launched its own appeal, requesting a new trial on all 26 counts of first-degree murder if the original verdict is overturned and arguing that the judge erred when he separated the cases.

Crown prosecutors have publicly stated if the original verdict is allowed to stand, they will not pursue a conviction on the other 20 counts.

Victims' families nervous about decision

Seventeen-year old Britney Frey, the daughter of Marnie Frey, will be in Vancouver when the appeal court hands down its decision.

"I'm just nervous because I really don't want to go back to court — [I'm] disappointed, upset,” she said.

But families of the dead women whose cases have not yet been heard in court are hoping the appeal will be successful, even if that means going through years of legal proceedings.

"We would hate to see Pickton actually win his appeal, but we want him to —only because that is the only way we foresee the other 20 girls getting justice," said Lori-Ann Ellis, whose sister-in-law, Cara Ellis, is one of the alleged victims in the outstanding cases.

Cara Ellis was 25 when she was last seen in January 1997, police said.

Dianne Rock, a mother of five, was nearly 10 years older than Ellis when she vanished in October 2001 at age 34.

Her sister, Lilliane Beaudoin, said it's not easy pulling for Pickton's defence team, but she believes it's her only choice.

"This way, at least I have some kind of hope that there's going to be a second trial and that my sister's case will be in the second trial," Beaudoin said.

"It's sad to say. Usually, I would go for the Crown counsel but not in this case."

Beaudoin said while having the convictions tossed out would undoubtedly be difficult for the families of the six women involved, it might be equally difficult for the families of the 20 women left in limbo.

"We need the justice that they received," she said.

Both sides argue judge erred in instructions

The appeal by the defence focused mainly on the instructions Justice Williams gave to the jury.

It contends Williams made a mistake when he initially instructed the jury they could convict Pickton if they were satisfied he acted either alone or in concert with others in the killings.

Pickton's lawyers argue there was no evidence presented at the trial that Pickton acted in concert with others.

The defence also argued the judge made a mistake when answering a question the jury asked on the sixth day of deliberations and by amending his instructions to them.

The question concerned the issue of whether Pickton could be considered guilty if the jury inferred he acted indirectly. The judge told the jury they could find Pickton guilty even if he didn't act alone, as long as they were convinced beyond a reasonable doubt he actively participated in the killings.

According to the Crown's notice of appeal, the judge's instructions to the jury erred when it came to certain evidence presented in relation to the question of whether the murders were planned and deliberate.

Errors don’t always mean new trial: legal expert

Benedet said there was so much evidence against Pickton that the judges might rule that although mistakes were made during the legal process, they weren't serious enough to warrant a new trial.

"They could also find that the defence is right, that there were errors in the judge's charge to the jury but that, ultimately, those errors did not affect the result," Benedet said.

"That given the overwhelming forensic and other evidence on behalf of the Crown, there was really no other reasonable conviction the jury could have come to other than to convict Pickton of murder."

Benedet said a new trial would mean choosing another jury and going through a "mountain” of forensic evidence that could take years.

With files from The Canadian Press